MEV vs dMEV vs MVHR vs PIV: The Plain-English UK Guide
What is MVHR?
MVHR stands for mechanical ventilation with heat recovery. It is a whole-house system that continuously extracts stale, damp air from kitchens, bathrooms and utility rooms, supplies filtered fresh air to living rooms and bedrooms, and passes the outgoing air through a heat exchanger so most of its warmth is recovered and handed to the incoming air. It ventilates your home; it does not heat it.
By VentRight Editorial · Last updated 2026-07-08 · Impartial · Sourced
How MVHR works: the two air streams cross in the heat exchanger, so most of the heat from the outgoing stale air is passed to the fresh incoming air.
How an MVHR unit works — labels
- 1Fresh air in — Cool, filtered air drawn in from outside.
- 2Supply to your home — That fresh air, now warmed by the heat exchanger, is sent to living rooms and bedrooms.
- 3Extract from your home — Warm, stale, damp air is pulled from kitchens, bathrooms and utility rooms.
- 4Exhaust to outside — The stale air, now cooled because its heat has been recovered, is expelled outside.
- 5Heat exchanger — The two air streams pass close together but never mix. Most of the heat moves from the outgoing air to the incoming fresh air.
A whole-house MVHR system supplies fresh air to living rooms and bedrooms and extracts stale air from wet rooms, all through ducting to a central unit.
Whole-house MVHR duct layout — labels
- unitMVHR unit — Usually in a loft or plant space. Fresh air enters and stale air is exhausted here.
- supplySupply ducts — Fresh, filtered air is ducted to the habitable rooms such as bedrooms and living rooms.
- extractExtract ducts — Stale, damp air is drawn from the wet rooms such as the kitchen and bathroom back to the unit.
What does MVHR stand for?
MVHR stands for mechanical ventilation with heat recovery. It is a whole-house ventilation system that extracts stale air from wet rooms, supplies fresh filtered air to habitable rooms, and recovers heat from the outgoing air with a heat exchanger, so the home is ventilated without throwing away most of the heat.
The four letters describe what the system does. Mechanical means fans move the air rather than relying on wind and gaps in the building. Ventilation means it provides the fresh air a home needs. Heat recovery means the warmth in the air being thrown out is captured and used to warm the fresh air coming in. The same technology is sometimes called whole-house heat recovery ventilation, but MVHR is the common UK term.
How does an MVHR system work?
An MVHR unit runs two separate air streams through a heat exchanger. Warm, stale air is drawn from kitchens, bathrooms and utility rooms and passed through the exchanger on its way outside. Cool fresh air is drawn in from outside, filtered, warmed by the outgoing air in the exchanger, then delivered to living rooms and bedrooms. The two streams never mix.
The unit is usually sited in a loft, plant cupboard or utility space and connected to each room by ducting. It runs continuously at a low background rate and boosts, automatically or on demand, when a kitchen or bathroom needs more extraction. Filters on the incoming air keep out pollen and particulates. Because the incoming air is pre-warmed by the outgoing air, the home stays ventilated in winter without the cold draught of an open window or the full heat loss of an extractor fan.
Is MVHR the same as air conditioning or heating?
No. MVHR is a ventilation system, not a heating or cooling system. It recovers heat that would otherwise be lost through ventilation, which lowers your heating demand, but it does not actively heat or cool a home the way a boiler, heat pump or air conditioner does. It is often paired with a heat pump, not a substitute for one.
This is the most common misunderstanding about MVHR. The heat exchanger only moves warmth from the outgoing air to the incoming air; it does not generate heat. On a cold day the fresh air arrives close to room temperature rather than fully warmed, so the heating system still does the heating. Under the Future Homes Standard many new homes will use a heat pump for heating and MVHR for ventilation together, each doing a different job.
Do I need MVHR in my home?
MVHR makes most sense in airtight homes, typically new builds and deep retrofits, where natural ventilation through gaps and trickle vents is no longer enough. In a leaky older home it can still work but is harder to justify. Building regulations require adequate ventilation in new and altered dwellings, and MVHR is one compliant way to provide it.
Approved Document F sets the ventilation a home must have; it does not mandate MVHR specifically. As homes are built more airtight to save energy under Part L, the case for mechanical ventilation grows, because there are fewer gaps for air to move through naturally. If you are choosing between system types, see our guide to MEV, dMEV, MVHR and PIV, which walks through which system suits which property.
Sources: GOV.UK
How much does an MVHR system cost?
A domestic MVHR system usually costs a few thousand pounds installed. Most UK installations fall between roughly 3,000 and 10,000 pounds, depending on the size of the home, the unit chosen, and whether it is fitted in a new build or retrofitted into an existing house. Retrofit is generally the more expensive route.
The total is made up of the unit itself, the ducting, the system design and the commissioning. New build is cheaper because ducting can be run before the rooms are finished. Our cost guide breaks down each element and its typical range, and explains why a cheap unit that is poorly installed can cost more in running costs and callbacks than a well specified one.
Questions
- Does MVHR work in an existing house?
- Yes. MVHR can be retrofitted into an existing house, but it is more disruptive and more expensive than fitting it during a new build or major renovation, because ducting has to be routed through finished rooms. It works best in reasonably airtight homes.
- Does MVHR make a house stuffy or noisy?
- A well designed and properly commissioned MVHR system should be quiet and should make a home feel fresher, not stuffy. Noise and poor air flow almost always come from bad duct design, undersized ducting or a system that was never properly commissioned, rather than from the technology itself.
- Does MVHR save money on heating?
- MVHR reduces the heat lost through ventilation by recovering warmth from the outgoing air, which lowers heating demand. The saving depends on how airtight your home is and how efficient the unit is. It is a ventilation system first; the heat recovery is a bonus, not a reason to install it on its own.
- Is MVHR required by building regulations?
- Building regulations require adequate ventilation in new and altered homes in the UK, but they do not specifically require MVHR. MVHR is one of several compliant ways to meet Approved Document F. In very airtight homes it is often the most practical option.
- Source: GOV.UK